1. Field of the Invention
This invention concerns an aircraft cockpit display device for information concerning surrounding traffic.
2. Discussion of the Background
In planes of a certain size and/or capable of transporting a preset number of passengers, the pilot has a device to help avoid collisions with other planes. This type of device is known as TCAS for “Traffic Alert and Collision Avoidance Systems,” which is therefore a system for air traffic collision alert and avoidance. This system makes it possible to monitor the air space close to the plane in question using radar. A display system makes it possible to display the surrounding aircraft detected by the system. In case of any risk of collision, the TCAS system issues alerts that are classified into two levels depending on the imminence of the risk of collision. Additionally, it establishes communication between the aircraft that are at risk of colliding with one another and suggests a maneuver suited to each of their situations. The system then gives each pilot instructions; for example, it orders one of the planes to ascend and the other to descend. The indications displayed on the screen corresponding to the TCAS are relatively abbreviated. Geometric shapes (lozenge, circle and square) are used depending on the proximity of the other plane and the imminence of the risk of collision.
Another system called ADS-B for “Automatic Dependent Surveillance-Broadcast” has been developed but is not yet in service. This system makes it possible to provide information concerning air space monitoring in an expanded space often exceeding 100 miles (1 mile=1,852 m). The information provided by the ADS-B is used to show the surrounding traffic on a display device. This makes it possible to give the crew a better understanding of the surrounding traffic. In the ADS-B system, each aircraft so equipped transmits information concerning its position, its speed, its direction, etc. This information may be received by air surveillance radar and also by planes equipped to receive and interpret the information transmitted.
Several applications are envisioned with an ADS-B system. The information collected by an ADS-B system can be used to supply a pilot with the position of surrounding aircraft by means of a display screen called CDTI for “Cockpit Display of Traffic Information.” This type of display can already be found in any airplane cockpit equipped with a TCAS. Thus, a first application allows the crew to better locate another airplane, for example under particular meteorological conditions. Another application is to make it possible to improve a visual approach by identifying the aircraft seen by the crew and providing it with information related to this aircraft. When the aircraft is on the ground, the system can also be used to indicate to the crew the situation of its own aircraft at the airport and also to provide information concerning the other aircraft surrounding its own aircraft. Before landing, during final approach, an ADS-B system also makes it possible to alert the pilot if the runway is occupied, for example. This type of system can also be used to help the pilot keep his distance from an aircraft preceding him both during flight phases and landing and takeoff.
There is also another system called TIS-B for “Traffic Information System-Broadcast.” The principle here consists in transmitting information developed by ground control. Thus, the planes benefit from information in the possession of ground control. This system allows wider coverage than the coverage obtained with ADS-B systems. However, the accuracy with a system using TIS-B can be different than that obtained with ADS-B. This can be explained more particularly by the delay necessary to retransmit the information received to the ground.